Milley said the shooter had arrived in Fort Hood in February from another institution in Texas. He said the shooter was undergoing treatment for depression, anxiety, and other disorders.

Milley also said the shooter used a semi automatic pistol that he had purchased recently. He said it's not clear if the shooter knew the victims or if the shooting was prompted by an argument. He said authorities are not ruling out terrorism.

Photo: Courtesy, Facebook

Image 1of/59

Caption

Close

Image 1 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 2 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 3 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 4 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 5 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 6 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 7 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 8 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 9 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 10 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 11 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 12 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 13 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 14 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 15 of 59

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Ivan Lopez, the shooter in the April 2, 2014 rampage on Fort Hood that killed 3 people and injured more than a dozen, is seen in an undated photo taken from his Facebook page.

Photo: Courtesy, Facebook

Image 16 of 59

Ivan Antonio Lopez, who authorities have identified as the shooter in the April 2, 2014 mass shooting on Fort Hood is seen in an undated drivers license photo provided by the Texas Department of Public Safety.

Ivan Antonio Lopez, who authorities have identified as the shooter in the April 2, 2014 mass shooting on Fort Hood is seen in an undated drivers license photo provided by the Texas Department of Public Safety.

Photo: COURTESY

Image 17 of 59

The flag flies at half mast at the Killeen City Cemetery on the morning after four Ft. Hood soldiers died in an incident on post. April 3, 2014.

The flag flies at half mast at the Killeen City Cemetery on the morning after four Ft. Hood soldiers died in an incident on post. April 3, 2014.

Photo: Billy Calzada, San Antonio Express-News

Image 18 of 59

Administrators and medical staff speak at a news conference about the Ft. Hood shooting victims being treated at Scott and White Hospital in Temple, Texas on April 3, 2014. From left are Dr. Alexander Thompson, Dr. Stephen Sibbitt, Dr. Matthew Davis and Larry Smith. less

Administrators and medical staff speak at a news conference about the Ft. Hood shooting victims being treated at Scott and White Hospital in Temple, Texas on April 3, 2014. From left are Dr. Alexander ... more

Photo: TOM REEL

Image 19 of 59

Dr. Matthew Davis, Trauma Director, describes patient injuries as administrators and medical staff speak at a news conference about the Ft. Hood shooting victims being treated at Scott and White Hospital in Temple, Texas on April 3, 2014. less

Dr. Matthew Davis, Trauma Director, describes patient injuries as administrators and medical staff speak at a news conference about the Ft. Hood shooting victims being treated at Scott and White Hospital in ... more

Photo: TOM REEL

Image 20 of 59

Dr. Matthew Davis (right) describes injuries with Dr. Stephen Sibbitt listening as administrators and medical staff speak at a news conference about the Ft. Hood shooting victims being treated at Scott and White Hospital in Temple, Texas on April 3, 2014. less

Dr. Matthew Davis (right) describes injuries with Dr. Stephen Sibbitt listening as administrators and medical staff speak at a news conference about the Ft. Hood shooting victims being treated at Scott and ... more

Photo: TOM REEL

Image 21 of 59

Administrators and medical staff speak at a news conference about the Ft. Hood shooting victims being treated at Scott and White Hospital in Temple, Texas on April 3, 2014.

Administrators and medical staff speak at a news conference about the Ft. Hood shooting victims being treated at Scott and White Hospital in Temple, Texas on April 3, 2014.

Lt. Gen. Mark Milley, middle, leaves a press conference on Wednesday night, April 2, 2014, after speaking about the shootings that happened at Fort Hood in the afternoon of the same day. The gunman killed three fellow soldiers before fatally shooting himself. less

Lt. Gen. Mark Milley, middle, leaves a press conference on Wednesday night, April 2, 2014, after speaking about the shootings that happened at Fort Hood in the afternoon of the same day. The gunman killed three ... more

Photo: Billy Calzada, San Antonio Express-News

Image 31 of 59

Lt. Gen. Mark Milley speaks on Wednesday night, April 2, 2014, about the shootings that happened at Fort Hood in the afternoon of the same day. The gunman killed three fellow soldiers before fatally shooting himself. less

Lt. Gen. Mark Milley speaks on Wednesday night, April 2, 2014, about the shootings that happened at Fort Hood in the afternoon of the same day. The gunman killed three fellow soldiers before fatally shooting ... more

Photo: Billy Calzada, San Antonio Express-News

Image 32 of 59

Lt. Gen. Mark Milley speaks on Wednesday night, April 2, 2014, about the shootings that happened at Fort Hood in the afternoon of the same day. The gunman killed three fellow soldiers before fatally shooting himself. less

Lt. Gen. Mark Milley speaks on Wednesday night, April 2, 2014, about the shootings that happened at Fort Hood in the afternoon of the same day. The gunman killed three fellow soldiers before fatally shooting ... more

Photo: Billy Calzada, San Antonio Express-News

Image 33 of 59

A Fort Hood solider looks on in the night at the main gate to the facility. Lt. Gen. Mark Milley spoke on Wednesday night, April 2, 2014, about the shootings that happened at the post in the afternoon of the same day. The gunman killed three fellow soldiers before fatally shooting himself. less

A Fort Hood solider looks on in the night at the main gate to the facility. Lt. Gen. Mark Milley spoke on Wednesday night, April 2, 2014, about the shootings that happened at the post in the afternoon of the ... more

Photo: Billy Calzada, San Antonio Express-News

Image 34 of 59

Traffic exits Fort Hood, Texas hours after the post was put on lockdown because of shootings that happened at Fort Hood in the afternoon on Wednesday, April 2, 2014. The gunman killed three fellow soldiers before fatally shooting himself. less

Traffic exits Fort Hood, Texas hours after the post was put on lockdown because of shootings that happened at Fort Hood in the afternoon on Wednesday, April 2, 2014. The gunman killed three fellow soldiers ... more

Photo: Billy Calzada, San Antonio Express-News

Image 35 of 59

Luci Hamlin and her husband, Spc. Timothy Hamlin, wait to get back to their home on the base following a shooting incident at Fort Hood, Texas, on Wednesday, April 2, 2014.

Luci Hamlin and her husband, Spc. Timothy Hamlin, wait to get back to their home on the base following a shooting incident at Fort Hood, Texas, on Wednesday, April 2, 2014.

Photo: Deborah Cannon, McClatchy-Tribune News Service

Image 36 of 59

Lucy Hamlin and her husband, Spc. Timothy Hamlin, wait for permission to re-enter the Fort Hood military base, where they live, following a shooting on base on Wednesday, April 2, 2014, in Fort Hood, Texas. One person was killed and 14 injured in the shooting, and officials at the base said the shooter is believed to be dead. The details about the number of people hurt came from two U.S. officials who spoke on condition of anonymity because they were not authorized to discuss the information by name. (AP Photo/ Tamir Kalifa) less

Lucy Hamlin and her husband, Spc. Timothy Hamlin, wait for permission to re-enter the Fort Hood military base, where they live, following a shooting on base on Wednesday, April 2, 2014, in Fort Hood, Texas. One ... more

Photo: Tamir Kalifa, Associated Press

Image 37 of 59

Photo: Harry Thomas

Image 38 of 59

Law enforcement officials with guns drawn approach a building at Ft. Hood where a shooting was reported Wednesday late afternoon. Bell County Sheriff's Office also reported a shooting on the post.

Law enforcement officials with guns drawn approach a building at Ft. Hood where a shooting was reported Wednesday late afternoon. Bell County Sheriff's Office also reported a shooting on the post.

Photo: SSG. Tim Reyes

Image 39 of 59

A Military Police officer runs toward the road leading to the Main Gate, Wednesday, April 2, 2014, as an active shooter remains at large at Fort Hood, Texas. Three people were killed and 14 injured in the shooting, and officials at the base said the shooter is believed to be dead. The details about the number of people hurt came from two U.S. officials who spoke on condition of anonymity because they were not authorized to discuss the information by name. less

A Military Police officer runs toward the road leading to the Main Gate, Wednesday, April 2, 2014, as an active shooter remains at large at Fort Hood, Texas. Three people were killed and 14 injured in the ... more

Photo: Rusty Schramm, Associated Press

Image 40 of 59

Members of the media wait outside of the Bernie Beck Gate, an entrance to the Fort Hood military base, for updates on a shooting that occurred inside on Wednesday, April 2, 2014 in Fort Hood, Texas.

Members of the media wait outside of the Bernie Beck Gate, an entrance to the Fort Hood military base, for updates on a shooting that occurred inside on Wednesday, April 2, 2014 in Fort Hood, Texas.

Photo: Tamir Kalifa, Associated Press

Image 41 of 59

Krystina Cassidy, left, and Dianna Simpson attempt to make contact with their husbands who are stationed inside Fort Hood while standing outside of the Bernie Beck Gate on Wednesday, April 2, 2014, in Fort Hood, Texas. At least one person was killed and 14 injured in the shooting, and officials at the base said the shooter is believed to be dead. (AP Photo/ Tamir Kalifa) less

Krystina Cassidy, left, and Dianna Simpson attempt to make contact with their husbands who are stationed inside Fort Hood while standing outside of the Bernie Beck Gate on Wednesday, April 2, 2014, in Fort ... more

Photo: Tamir Kalifa, Associated Press

Image 42 of 59

Krystina Cassidy and Dianna Simpson attempt to make contact with their husbands who are stationed inside Fort Hood, while standing outside of the Bernie Beck Gate, on Wednesday, April 2, 2014, in Fort Hood, Texas. One person was killed and 14 injured in a shooting Wednesday at Fort Hood, and officials at the base said the shooter is believed to be dead. less

Krystina Cassidy and Dianna Simpson attempt to make contact with their husbands who are stationed inside Fort Hood, while standing outside of the Bernie Beck Gate, on Wednesday, April 2, 2014, in Fort Hood, ... more

Photo: Tamir Kalifa, Associated Press

Image 43 of 59

A police officer checks drivers' IDs outside the main gate at Fort Hood, Texas, after a shooting at the Army base Wednesday, April 2, 2014. One person was killed and at least 14 injured in a shooting Wednesday at Fort Hood. (AP Photo/Austin American-Statesman, Deborah Cannon) AUSTIN CHRONICLE OUT, COMMUNITY IMPACT OUT, MAGS OUT; NO SALES; INTERNET AND TV MUST CREDIT PHOTOGRAPHER AND STATESMAN.COM less

A police officer checks drivers' IDs outside the main gate at Fort Hood, Texas, after a shooting at the Army base Wednesday, April 2, 2014. One person was killed and at least 14 injured in a shooting Wednesday ... more

Photo: Deborah Cannon, Associated Press

Image 44 of 59

A Fort Hood Police Officer stops a vehicle near the main gate, Wednesday, April 2, 2014, as the military base was placed on lock down in Fort Hood, Texas. One person was killed and 14 injured in the shooting, and officials at Fort Hood said the shooter is believed to be dead. The details about the number of people hurt came from two U.S. officials who spoke on condition of anonymity because they were not authorized to discuss the information by name. less

A Fort Hood Police Officer stops a vehicle near the main gate, Wednesday, April 2, 2014, as the military base was placed on lock down in Fort Hood, Texas. One person was killed and 14 injured in the shooting, ... more

Photo: Rusty Schramm, Associated Press

Image 45 of 59

A military police officer stops a car at Fort Hood, Texas, after a shooting on the Army base Wednesday, April 2, 2014. At least one person was killed and at least 14 injured in a shooting Wednesday at Fort Hood. AUSTIN CHRONICLE OUT, COMMUNITY IMPACT OUT, MAGS OUT; ; INTERNET AND TV MUST CREDIT PHOTOGRAPHER AND STATESMAN.COM less

A military police officer stops a car at Fort Hood, Texas, after a shooting on the Army base Wednesday, April 2, 2014. At least one person was killed and at least 14 injured in a shooting Wednesday at Fort ... more

Photo: Deborah Cannon, AP

Image 46 of 59

Vehicles are checked outside of the Bernie Beck Gate, Wednesday, April 2, 2014, in Fort Hood, Texas. One person was killed and 14 injured in a shooting at Fort Hood, and officials at the base said the shooter is believed to be dead. less

Vehicles are checked outside of the Bernie Beck Gate, Wednesday, April 2, 2014, in Fort Hood, Texas. One person was killed and 14 injured in a shooting at Fort Hood, and officials at the base said the shooter ... more

A medical evacuation helicopter makes an approach to Fort Hood, Texas, Wednesday, April 2, 2014, as a Texas Department of Public Safety Helicopter, left, flies behind. One person was killed and 14 injured in a shooting at the military base, and officials said the shooter is believed to be dead. The details about the number of people hurt came from two U.S. officials who spoke on condition of anonymity because they were not authorized to discuss the information by name. less

A medical evacuation helicopter makes an approach to Fort Hood, Texas, Wednesday, April 2, 2014, as a Texas Department of Public Safety Helicopter, left, flies behind. One person was killed and 14 injured in a ... more

Photo: Rusty Schramm, Associated Press

Image 49 of 59

Members of the media wait outside of the Bernie Beck Gate, an entrance to the military base, for updates on a shooting that occurred inside on Wednesday, April 2, 2014, in Fort Hood, Texas.

Members of the media wait outside of the Bernie Beck Gate, an entrance to the military base, for updates on a shooting that occurred inside on Wednesday, April 2, 2014, in Fort Hood, Texas.

Photo: Tamir Kalifa, Associated Press

Image 50 of 59

Military personnel and civilians wait in a parking lot outside of the Fort Hood military base for updates about the shooting that occurred inside on Wednesday, April 2, 2014, in Fort Hood, Texas.

Military personnel and civilians wait in a parking lot outside of the Fort Hood military base for updates about the shooting that occurred inside on Wednesday, April 2, 2014, in Fort Hood, Texas.

Photo: Tamir Kalifa, Associated Press

Image 51 of 59

A police officer checks drivers' IDs outside the main gate at Fort Hood, Texas, after a shooting at the Army base Wednesday, April 2, 2014. One person was killed and at least 14 injured in a shooting Wednesday at Fort Hood. (AP Photo/Austin American-Statesman, Deborah Cannon) AUSTIN CHRONICLE OUT, COMMUNITY IMPACT OUT, MAGS OUT; NO SALES; INTERNET AND TV MUST CREDIT PHOTOGRAPHER AND STATESMAN.COM less

A police officer checks drivers' IDs outside the main gate at Fort Hood, Texas, after a shooting at the Army base Wednesday, April 2, 2014. One person was killed and at least 14 injured in a shooting Wednesday ... more

Photo: Deborah Cannon, Associated Press

Image 52 of 59

President Barack Obama pauses as he speaks about the shooting at Fort Hood, Wednesday, April 2, 2014, in Chicago. (AP Photo/Carolyn Kaster)

President Barack Obama pauses as he speaks about the shooting at Fort Hood, Wednesday, April 2, 2014, in Chicago. (AP Photo/Carolyn Kaster)

Photo: Carolyn Kaster, Associated Press

Image 53 of 59

President Barack Obama pauses as he speaks about the shooting at Fort Hood, Wednesday, April 2, 2014, in Chicago. (AP Photo/Carolyn Kaster)

President Barack Obama pauses as he speaks about the shooting at Fort Hood, Wednesday, April 2, 2014, in Chicago. (AP Photo/Carolyn Kaster)

Photo: Carolyn Kaster, Associated Press

Image 54 of 59

Members of the media wait outside of the Bernie Beck Gate, an entrance to the Fort Hood military base, for updates on a shooting that occurred inside on Wednesday, April 2, 2014, in Fort Hood, Texas. (AP Photo/Tamir Kalifa) less

Members of the media wait outside of the Bernie Beck Gate, an entrance to the Fort Hood military base, for updates on a shooting that occurred inside on Wednesday, April 2, 2014, in Fort Hood, Texas. (AP ... more

Photo: Tamir Kalifa, Associated Press

Image 55 of 59

Members of the media wait outside of the Bernie Beck Gate, an entrance to the Fort Hood military base, for updates on a shooting that occurred inside on Wednesday, April 2, 2014, in Fort Hood, Texas. (AP Photo/Tamir Kalifa) less

Members of the media wait outside of the Bernie Beck Gate, an entrance to the Fort Hood military base, for updates on a shooting that occurred inside on Wednesday, April 2, 2014, in Fort Hood, Texas. (AP ... more

Photo: Tamir Kalifa, Associated Press

Image 56 of 59

Local and Military police direct traffic outside of an entrance to Fort Hood following reports of an active shooting on the military base in Wednesday, April 2, 2014, in Fort Hood, Texas. (AP Photo/Tamir Kalifa) less

Local and Military police direct traffic outside of an entrance to Fort Hood following reports of an active shooting on the military base in Wednesday, April 2, 2014, in Fort Hood, Texas. (AP Photo/Tamir ... more

Photo: Tamir Kalifa, Associated Press

Image 57 of 59

U.S. Secretary of Defense Chuck Hagel speaks during a news conference on the flight deck of the USS Anchorage (LPD-23), an amphibious transport dock ship, after a tour with his counterparts from Southeast Asia April 2, 2014 at Joint Base Pearl Harbor-Hickam in Honolulu, Hawaii. Secretary Hagel is in Hawaii to host a meeting of defense ministers from the Association of Southeast Asian Nations (ASEAN). A MV-22 Osprey tiltrotor V/STOL aircraft is in the background, (AP Photo/Alex Wong, Pool) less

U.S. Secretary of Defense Chuck Hagel speaks during a news conference on the flight deck of the USS Anchorage (LPD-23), an amphibious transport dock ship, after a tour with his counterparts from Southeast Asia ... more

Photo: Alex Wong, Associated Press

Image 58 of 59

U.S. Secretary of Defense Chuck Hagel receives an update on the phone on the shooting at Fort Hood in Texas, as he was on a tour of the USS Anchorage, an amphibious transport dock ship, with his counterparts from Southeast Asia on Wednesday, April 2, 2014, at Joint Base Pearl Harbor-Hickam in Honolulu, Hawaii. (AP Photo/Alex Wong, Pool) less

U.S. Secretary of Defense Chuck Hagel receives an update on the phone on the shooting at Fort Hood in Texas, as he was on a tour of the USS Anchorage, an amphibious transport dock ship, with his counterparts ... more

Photo: Alex Wong, Associated Press

Image 59 of 59

Four dead in Fort Hood shooting, including gunman

1 / 59

Back to Gallery

Fort Hood's director of emergency services received an initial report that the shooter was dead around 6:30 p.m. “Tonight, Texans' hearts are once again very heavy,” said Sen. John Cornyn in a statement. “The scenes coming from Fort Hood today are sadly too familiar and still too fresh in our memories. No community should have to go through this horrific violence once, let alone twice.”

Michelle Lee, spokeswoman for the FBI in San Antonio, said the FBI had “no indication” the shooting at Fort Hood is related to a alert sent by the agency in recent days regarding an Army recruit named Muhammad Abdullah Hassan, aka “Booker,” who was discharged in February from a Kansas City, Mo., base.

An alert sent March 20 by the Kansas City FBI Division that was titled “Planned Fort Hood-inspired Jihad against US Soldiers by Army Recruit” and stated Booker had publicly stated his intent to harm soldiers, according to Fox News.

Lee, though, confirmed Booker has been deemed not to be a threat after investigators met with him.

“Obviously, we're all following it closely,” President Barack Obama said in a statement to reporters in Chicago. “The situation is fluid right now. But my national security team in close contact with not just the Defense Department but with the FBI. They are working with folks on the ground to determine exactly what happened and ensure that everybody is secure. And I want to just assure all of us we going to get to bottom of exactly what happened.”

Fort Hood has a population of more than 50,000, according to the 2010 U.S. Census.

The post was the scene of a shooting nearly five years ago that left 13 people dead, 12 of them soldiers, and dozens of others wounded.

A Fort Hood psychiatrist, Maj. Nidal Hasan, was given the death sentence in that case last summer.

“Any shooting is troubling,” Obama said. “Obviously this reopened pain of what happened at Fort Hood five years ago. We know these families, we know the service to their country and the sacrifices that they make. Obviously our thoughts and prayers are with the entire community and we are going to do everything we can to make sure the community of Fort Hood has what it needs to deal with a tough situation but also any potential aftermath.”

Residents on the base described a chaotic, noisy, scary scene Wednesday afternoon.

Brooke Chatha, 22, was in the kitchen doing the dishes when she heard base alarms sounding.

“Those alarms go off a lot, thought it was just another drill,” said Chatha, who lives on the base with her 4-month-old child and her husband, a soldier who works in the base's motor pool.

A friend started texting her, asking if she was OK.

“That's when I started looking up and everything that was going on,” she told the Houston Chronicle. That was about 5 p.m.

“It's a little frustrating,” she said. Her husband was still at work, and his commanders were talking about not releasing him until 2 a.m., she said.

“He was texting me a little bit [after the shooting], he hasn't texted since, I have no idea if he knows anyone who got hurt,” she said.

As she was speaking, the base's sirens went off again.

She lives by the base's main gate. Normally, toward the end of the day, traffic streams out of the base about 5 p.m.

“Nobody was outside, there was nothing. I was told by a friend not to go outside...there was a helicopter flying right above our house and all you could here were sirens — and they went on for an hour or two.”